refactor container collector into subpackage

collector/docker.go

@@ -0,0 +1,84 @@
+package collector
+
+import (
+	api "github.com/fsouza/go-dockerclient"
+)
+
+// Docker collector
+type Docker struct {
+	Metrics
+	stream     chan Metrics
+	done       chan bool
+	lastCpu    float64
+	lastSysCpu float64
+}
+
+func NewDocker(client *api.Client, id string) *Docker {
+	c := &Docker{
+		Metrics{},
+		make(chan Metrics),
+		make(chan bool),
+		0,
+		0,
+	}
+
+	stats := make(chan *api.Stats)
+
+	go func() {
+		opts := api.StatsOptions{
+			ID:     id,
+			Stats:  stats,
+			Stream: true,
+			Done:   c.done,
+		}
+		client.Stats(opts)
+	}()
+
+	go func() {
+		for s := range stats {
+			c.ReadCPU(s)
+			c.ReadMem(s)
+			c.ReadNet(s)
+			c.stream <- c.Metrics
+		}
+	}()
+
+	return c
+}
+
+func (c *Docker) Stream() chan Metrics {
+	return c.stream
+}
+
+// Stop collector
+func (c *Docker) Stop() {
+	c.done <- true
+}
+
+func (c *Docker) ReadCPU(stats *api.Stats) {
+	ncpus := float64(len(stats.CPUStats.CPUUsage.PercpuUsage))
+	total := float64(stats.CPUStats.CPUUsage.TotalUsage)
+	system := float64(stats.CPUStats.SystemCPUUsage)
+
+	cpudiff := total - c.lastCpu
+	syscpudiff := system - c.lastSysCpu
+
+	c.CPUUtil = round((cpudiff / syscpudiff * 100) * ncpus)
+	c.lastCpu = total
+	c.lastSysCpu = system
+}
+
+func (c *Docker) ReadMem(stats *api.Stats) {
+	c.MemUsage = int64(stats.MemoryStats.Usage)
+	c.MemLimit = int64(stats.MemoryStats.Limit)
+	c.MemPercent = round((float64(c.MemUsage) / float64(c.MemLimit)) * 100)
+}
+
+func (c *Docker) ReadNet(stats *api.Stats) {
+	var rx, tx int64
+	for _, network := range stats.Networks {
+		rx += int64(network.RxBytes)
+		tx += int64(network.TxBytes)
+	}
+	c.NetRx, c.NetTx = rx, tx
+}